The density of the healthy, catabolic and EPOR-active chondrocytes (C(r, t), ST(r, t), SA(r, t)) at t = 2, 4, 6, 8, 10 days with ε = 0.4 and σP = 4.2 · 10−5 (light strain with low EPO production). We see that with relatively light strain we have a relatively narrow penumbra (the region dominated by ST and SA) compared to cases of higher strain with low EPO, constituting a relatively narrow lesion.